package com.example.demo.config;

/**
 * 数据源切换AOP
 *
 * @ClassName DataSourceAspect
 * @Author: HanQiCheng
 * @DateTime: 2022/8/15 11:42
 */
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import java.util.Objects;

@Aspect
@Component
@Order(1)
public class DataSourceAspect {

    @Pointcut("@annotation(com.example.demo.config.DataSource) || @within(com.example.demo.config.DataSource)")
    public void dataSourcePointCut() {}

    @Around("dataSourcePointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        DataSource dataSource = getDataSource(point);
        if (dataSource != null){
            DataSourceUtil.setDB(dataSource.value());
        }
        try {
            return point.proceed();
        } finally {
            DataSourceUtil.clearDB();
        }
    }

    /**
     * 获取需要切换的数据源
     */
    public DataSource getDataSource(ProceedingJoinPoint point) {
        MethodSignature signature = (MethodSignature) point.getSignature();
        DataSource dataSource = AnnotationUtils.findAnnotation(signature.getMethod(), DataSource.class);
        if (Objects.nonNull(dataSource)) {
            return dataSource;
        }
        return AnnotationUtils.findAnnotation(signature.getDeclaringType(), DataSource.class);
    }
}

